Qt 5.3.2 QRadioTuner: radio example failed to detect radio at /dev/radio0

I'm running Qt Everywhere 5.3.2 compiled on a beaglebone black running Debian 7.6 kernel 3.14
I'm trying to get the radio example to detect and use my InstantFM Music USB radio tuner.
The radio tuner interface is in /dev/radio0. I can use
v4l2-ctl -d /dev/radio0 -c volume=10,mute=0 -f 91.1 --all
to tune the device, so it is DDS compatible (I think tat's what it means).
I can stream the audio using
arecord -D hw:1,0 -c2 -fS16_LE -r48000 | aplay
However, when I run the example multimedia/radio/radio it fails to find the tuner with the message: radio not found
Is there an environment variable to tell QRadioTuner which dev device to open?